Directions

Turn out onto a work surface and gather the crumbs together. Shape into a disk. wrap in plastic and refrigerate for an hour.

FILLING AND STREUSEL:.

Mix flour with walnuts, both sugars, 1/4 teaspoon salt and cinnamon in a medium bowl.

In a small skillet, cook five tablespoons butter until golden brown. Pour over flour mixture and toss gently until crumbly. Refrigerate.

Preheat oven to 375°F.

In a large skillet, bring the maple syrup, vanilla bean and seeds to a boil. Cook over moderately high heat for three minutes.

Whisk in the remaining butter and 1/4 teaspoon salt.

Add half of the apples and cook until beginning to soften. Transfer apples (with slotted spoon) to a platter. Repeat with remaining apples. Let cool. Discard the vanilla bean and scrape pan juices into a bowl.

On a lightly floured work surface, roll out the pastry to a 15-inch round, 1/8 inch thick.

Transfer to a baking sheet and refrigerate 15 minutes.

Brush the egg wash in a 2-inch band around the edge of the dough.

Spread apples on the pastry. Add any pan juices.

Fold the border up over the apples, leaving the center exposed.

Sprinkle the streusel topping over the apples in the center and brush the pastry with the egg wash.